Bore (also known as borehole ) is the technical term for a mostly round, rarely non-round, recess or breakthrough. The prerequisite is the production of the hole using rotating tools, so-called drills . Only in exceptions such as drill eroding or laser drilling is one also speaks of a hole.
Holes can be created both by hand with a hand drill and on a number of machine tools , such as drill , lathe , milling machine . So-called jig boring mills have been developed for workpieces of all sizes for particularly precise bores . Boreholes can also be driven into the ground or through massive rocks, for example when building wells and tunnels as well as in oil and gas production . The machines, equipment and systems for this encompass a broad spectrum from simple well drilling machines to highly complex drilling systems , drilling rigs or drilling ships . What all the holes have in common is that they are made with rotating tools and the mechanical removal of chips or fragments. But also holes made by spark erosion , vibratory lapping or by laser are called bores. In many cases, however, it is an engraving.
If a thread is made in a hole , it is called a threaded hole .
In technical drawings , special presentation rules apply to the presentation and dimensioning of bore holes and threads. In the past z. B. the symbol ø for the diameter ( nominal diameter ) only entered in the dimension of the drawing if the circular shape of the hole was not immediately recognizable, d. H. with the hidden representation or a sectional view of the hole.